Thunderstorm Wind in Brown County, Illinois

Widespread wind damage from the north side of Mt. Sterling to south of Hersman. Numerous trees, tree limbs, power poles and power lines were blown down. Several businesses and homes, especially on the south side of Mt. Sterling, sustained roof damage from fallen trees and tree limbs. One of the baseball dugouts at the high school was destroyed, with other minor damage around the school campus. A couple of trees fell onto unoccupied vehicles causing major damage.

On the evening of July 9th, intense thunderstorms developed rapidly along a warm front draped from northwest to southeast across the area. There were two rounds of thunderstorms, the first being discrete, rotating storms called supercells. These supercell thunderstorms dropped large hail across portions of western Illinois (Mt. Sterling area) and also across the western St. Louis metro area. Hail in excess of 2 inches was noted in both of these supercells. Over time, the storms congealed into a large complex of thunderstorms known as a mesoscale convective complex (MCC). This line of storms contained damaging, sometimes destructive winds as they quickly pushed southeast across east-central Missouri into southwest Illinois. The worst damage was noted from Rensselaer, MO southward to Perry, MO, where straight-line winds of 90 mph were found. This same line of storms also affected the St. Louis metro area, bringing widespread 60-70 mph winds across the metro causing many large tree limbs to fall and many to be without power.